Luma, Lumanace

Luma and Luminace

Luminace: The eyes perception of light intensity (optical perception)

Luma: The measurement of the intensity of the monochrome portion of an image. mesured in volts. (electrical signal) 

http://www.slideshare.net/caffscho11/luminace-and-luma

100% Luma value is broadcast safe, cameras capture up to 110% called super-white which is not broadcast safe.

 

Reduction of light can be achieved with a Neutral Density Filter which cuts the amount of light without changing the colors.